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Bread Mold Lab

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Noah Biniek

on 3 June 2013

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Transcript of Bread Mold Lab

Bread Mold Growth Lab Purpose: The purpose of this lab is to determine the influence certain variables have on the growth of bread mold over 9 days. The lab investigates the independent variables: light vs. dark, wet vs. dry, 24°C vs. 4°C vs. -18°C, and pH 7 vs. pH 2. The qualitative data gathered included whether mold grew, how long it took to grow, and which kinds of mold grew (rhizopus, aspergillus, or penicillium). Materials: Marker Ruler Pen Bread Knife 21 Plastic Bags Tablespoon Sourdough Bread Water Bottle (pH 7) Lemon Juice (pH 2) Bread Cube Dimensions (2" x 1 3/4" x 1") Procedure: 1. Unwrap sourdough bread from packaging.
2. Measure with the ruler and use the bread knife to cut 18 bread cubes at the dimensions
2" x 1 3/4" x 1" on the cutting board.
3. Separate the plastic bags and bread cubes into 6 groups of 3.
4. Label the groups of bags with a marker: L/W (Light/Water), DRK (Dark), DRY (Dry),
FRG (Fridge), FZR (Freezer), and LMN (Lemon).
5. Pour 4 tbsp of water onto each of the bread cubes (excluding the DRY cubes).
6. Follow the directions for each of the experimental variables. Cutting Board Ipad Camera Basic Setup: Temperature (24°C vs. 4°C vs. -18°C) Dark vs. Light Wet vs. Dry pH (Water [7] vs. Lemon Juice [2]) 1. Place the DRK and L/W bread cubes in the respective bags.
2. Place the DRK bags in a dark environment (dark box) and the L/W
bags in an environment with constant light and temperature (lamp).
3. Record observations every every day for nine days with pen (mold
growth?; type[s] of mold?) and take a picture every three days. 1. Place the DRY bread cubes in the respective bags.
2. Place the DRY bags with the L/W bags in the environment with
constant light and temperature.
3. Refer to the the L/W bags for the "wet" variable.
4. Record observations every day for nine days with pen (mold
growth?; type[s] of mold?) and take a picture every three days. Lamp Dark Box Day 0 Day 3 Day 0 Day 6 Day 9 Day 0 Day 3 Day 3 Day 0 Day 3 Day 6 Day 6 Day 6 Day 9 Day 9 Day 9 Hypothesis: Further Setup: Further Setup: Hypothesis: Further Setup: Hypothesis: Further Setup: Hypothesis: 1. Place the FZR and FRG bread cubes in the respective bags.
2. Place the FZR bags in the freezer (-18°C) and the FRG bags in the
fridge (4°C).
3. Refer to the the DRK bags for the "24°C" variable.
4. Record observations every every day for nine days with pen (mold
growth?; type[s] of mold?) and take a picture every three days. 1. Pour 2 tbsp of lemon juice onto the LMN bread cubes.
2. Place the LMN bread cubes in the respective bags.
3. Refer to the the L/W bags for the "pH 7" variable.
4. Record observations every every day for nine days with pen (mold
growth?; type[s] of mold?) and take a picture every three days. When bread is in an environment with constant light, mold will grow faster and more varied in opposition to a dark environment, because of more available light energy. When bread is wet, mold will grow faster and more varied in opposition to dry bread, because of the nutrients water provides to mold. When bread is in a colder environment (<5°C), mold growth will be inhibited, because mold requires room temperature to grow. When bread's pH is lowered by lemon juice (pH 2), mold growth will be inhibited, because mold cannot grow in a very acidic environment. Analysis: Table of Qualitative Observations Of Mold Growth in Each Environment Conclusion: Independent Variables: Light
Dark
Wet
Dry
24°C 4°C
-18°C
pH 7
pH 2 Dependent Variables: Mold growth
Speed of mold growth
Types of mold growth In this lab, the influence of certain variables on bread mold growth was determined. 18 cubes of bread were exposed to the following variables in groups of 3: light/wet/pH 7, dark/room temp., dry, lemon (pH 2), fridge, and freezer. The groups of bread were then examined every day for nine days. The dependent variables examined included whether there was mold growth, which types of mold grew, and how soon did it begin to grow. In the first experiment testing the effect of light vs. dark, the hypothesis was: when bread is in an environment with constant light, mold will grow faster and more varied in opposition to a dark environment, because of more available light energy. The initial hypothesis was incorrect. They both grew the three types of mold being studied (rhizopus, aspergillus, and penicillium), and the mold in the dark environment began growing a day earlier. A possible error in this experiment was light exposure to the bread in the dark environment when a picture was taken. The sudden exposure may have triggered a change in mold metabolism. In the second experiment testing the effect of wet vs. dry, the hypothesis was: when bread is wet, mold will grow faster and more varied in opposition to dry bread, because of the nutrients water provides to mold. The initial hypothesis was correct. The wet bread grew all three types of mold, whereas, the dry bread only grew aspergillus. The wet bread began growing three days earlier than the dry bread. A possible error in this experiment was moisture in the air sealed into the "dry" bags. If there truly was no water, mold growth may have been inhibited completely. In the third experiment testing the effect of temperature, the hypothesis was: when bread is in a colder environment (<5°C), mold growth will be inhibited, because mold requires room temperature to grow. The initial hypothesis was correct. When the bread was placed in the fridge at 4°C and in the freezer at -18°C, no mold grew. For more accurate and thorough results, bread would need to be placed in many other temperatures to determine the optimal temperature for mold growth. In the fourth experiment testing the effect of pH, the hypothesis was: when bread's pH is lowered by lemon juice (pH 2), mold growth will be inhibited, because mold cannot grow in a very acidic environment. The initial hypothesis was partially incorrect. When the bread was exposed to lemon juice, mold growth was slower but not completely inhibited. A possible error in this experiment was whether the lowered pH affected the mold growth or a chemical in the lemon juice. For more accurate and thorough results, bread would need to be placed in many other environments with various pHs to find the optimal pH and the effect of basicity and acidity on mold growth. As can be seen by the data from the four experiments, many variables can affect mold growth. In conclusion to this lab, four statements can be determined from the experiments. When bread is in a dark environment, mold will grow faster in opposition to a light environment. When bread is wet, mold will grow faster and more varied in opposition to dry bread. When bread is in a colder environment (<5°C), mold growth will be inhibited. When bread's pH is lowered by lemon juice (pH 2), mold growth will be slower. Citation: https://www.khanacademy.org/partner-content/mit-k12/mit-k12-biology/v/bread-mold-kills-bacteria
http://www.ehow.com/list_5956459_different-kinds-bread-mold.html
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